This invention is generally directed to processes for the preparation of alkoxy-bridged metallophthalocyanine dimers, such as alkoxy-bridged metallophthalocyanine dimers of a trivalent metal of the Formula ##STR1## wherein M is a trivalent metal, and R is an alkyl group or an alkyl ether group, reference copending patent application U.S. Ser. No. 239,432 the disclosure of which is totally incorporated herein by reference.
The alkoxy-bridged metallophthalocyanine dimers of Formula 1 are believed to be novel phthalocyanine dimers, or diphthalocyanines characterized by an alkoxy (--O--R--O) bridge between the two metallophthalocyanine rings. The structure between the two oxygen molecules of the bridge is determined by the diol used in the synthesis: The trivalent metal in the phthalocyanine dimer structure can be aluminum, gallium or indium, or trivalent transitional metals, such as Mn(III), Fe(III), Co(III), Ni(III), Cr(III), and the like.
In embodiments, the present invention is directed to processes for the preparation of specific alkoxy-bridged metallophthalocyanine dimers, including alkoxy-bridged gallium phthalocyanine dimers. More specifically, the present invention in embodiments is directed to processes for the preparation of alkoxy bridged metallophthalocyanine dimers directly from known phthalocyanine precursors such as orthophthalodinitrile or 1,3-diiminoisoindoline. The alkoxy-bridged metallophthalocyanine dimers can be obtained by the reaction of orthophthalodinitrile or 1,3-diiminoisoindoline with a trivalent metal alkoxide and a diol. During the aforementioned reaction, the diol, which can act also as a solvent for the reaction, is chemically incorporated into the phthalocyanine product enabling the formation of an alkoxy-bridged metallophthalocyanine dimer of Formula 1 C.sub.32 H.sub.16 N.sub.8 MOROMN.sub.8 H.sub.16 C.sub.32 wherein M is a trivalent metal and the alkoxy bridge O--R--O) contains an alkyl group, such as ethyl, propyl or butyl, which originates from the diol selected.
The alkoxy-bridged metallophthalocyanine dimers can also be obtained by the reaction of ortho-phthalodinitrile or 1,3-diiminoisoindoline with other complexes of trivalent metals, such as the triacetates, for example gallium acetate, and the triacetylacetonates, such as gallium acetylacetonate, and a diol.
Processes for the preparation of alkoxy-bridged metallophthalocyanine dimers can also be accomplished when the trivalent metal alkoxide is not readily available or stable by preparing the trivalent metal alkoxide as part of the phthalocyanine synthesis, and selecting the freshly prepared metal alkoxide for the reaction with orthophthalodinitrile or 1,3-diiminoisoindoline, and a diol to form the alkoxy-bridged metallophthalocyanine dimer.
In embodiments, the present invention is also directed to an efficient and economical process for the preparation of alkoxy-bridged metallophthalocyanine dimers by the in situ formation of trivalent metal alkoxides from metal halides. The metal halides are about one-tenth the cost and readily available from sources like certain United States corporations (such as APL Engineered Materials, Urbana, Ill., and Gallard-Schlesinger Industries, Carle Place, N.Y.) which supply inorganic or organometallic chemicals on multikilogram scale from stock supplies, compared to the corresponding trivalent metal alkoxides, acetates and acetylacetonates, which are usually considered special order components and which are generated on less than one kilogram scale. Thus, the alkoxy-bridged metallophthalocyanine dimers of the present invention can be prepared in efficient, economical and high yield, for example about 70 to about 85 percent, from metal halides.
Alternatively, the alkoxy-bridged metallophthalocyanine dimers can be prepared by first preparing a halometallo phthalocyanine of a trivalent metal, which is then hydrolyzed to the corresponding hydroxymetallo phthalocyanine. The hydroxymetallo phthalocyanine can be converted to an alkoxy-bridged metallophthalocyanine dimer by reaction with a diol in the presence of excess diol or another solvent.
In embodiments, the present invention relates to processes for obtaining alkoxy-bridged gallium phthalocyanines as representatives of a new class of alkoxy-bridged metallophthalocyanine dimers of Formula 1.
The alkoxy-bridged metallophthalocyanine dimers obtained with the processes of the present invention, such as alkoxy-bridged gallium phthalocyanine dimers, can be selected as photogenerator components in photoresponsive or photoconductive imaging members reference copending patent applications U.S. Ser. No. 239,432 and U.S. Ser. No. 233,834 the disclosures of which are totally incorporated herein by reference. These imaging members may be layered photoconductive imaging members, and may contain separate charge transport layers, especially hole transport layers containing hole transport molecules. The imaging members containing alkoxy-bridged metallophthalocyanine dimers possess infrared photosensitivity, and are sensitive in the wavelength regions of from about 650 to about 850 nanometers, therefore, diode lasers can be selected as the light source. The layered photoconductive imaging members can be selected for a number of different known imaging and printing processes including, for example, electrophotographic imaging processes, especially xerographic imaging and printing processes wherein negatively charged or positively charged images are rendered visible using toner compositions of appropriate charge polarity. The alkoxy-bridged metallophthalocyanine dimers can be used as precursors for the preparation of other phthalocyanines such as hydroxy metallophthalocyanines, which phthalocyanines may be selected as the photogenerating pigment in photoresponsive imaging members. Further, the alkoxy-bridged metallophthalocyanines obtained with the processes of the present invention can also be selected as precursors for the preparation of other phthalocyanine compounds, such as hydroxymetallo phthalocyanines, for example hydroxygallium phthalocyanine, as described in copending application U.S. Ser. No. (not yet assigned D/93606).
Certain metallophthalocyanines containing two phthalocyanine rings in the molecule have been described in the literature. Early work by P. A. Barrett et al. in J. Chem Soc., 1717, 1936 cites the discovery of (AlPc).sub.2 O, a .mu.-oxo bridged aluminum phthalocyanine of Formula 2. ##STR2##
The formation of a similar compound of trivalent Fe, (Fe Pc).sub.2 O by aeration of FePc was described by C. Ercolani et al. in Inorg. Chem., 25, 3972, 1986.
Bis(phthalocyaninato)lanthanide(III) complexes, also described as lanthanide diphthalocyanines [L(Pc).sub.2 ] have been reported by I. S. Kirin et al. in Russ. J. Phys. Chem (Engl Transl), 41, 251, 1967. The lutetium phthalocyanine dimer has been reviewed in the literature, for example for its electrochromic properties. Phthalocyanines Properties and Applications, 1989, VCH Publishers, Inc., edited by C. C. Leznoff and A. B. P. Lever, describes a series of these materials, with the corresponding original references.
Diphthalocyanines of tetravalent metals, such as stanium, Sn(Pc).sub.2, and zirconium, Zr(Pc).sub.2, of the structure shown in Formula 3, have been synthesized and described by W. R. Bennet et al. in Inorg Chem., 12, 930, 1973 and J. Silver et al. in Polyhedron, 8, 1631, 1989. ##STR3## wherein M is a metal.
In the aforementioned documents, there is believed to be no disclosure of alkoxy-bridged metallophthalocyanine dimers, such as alkoxy-bridged gallium phthalocyanine dimers, or processes for the preparation thereof.
Many halometallo- and hydroxymetallo phthalocyanines of trivalent metals, such as Al, Ga and In, are disclosed in the literature, for example in The Phthalocyanines, vol. I and II, F. H. Moser and A. L. Thomas, CRC Press Inc., 1983 and by J. P. Linsky et al. in Inorg. Chem. 19, 3131, 1980.
In Bull. Soc. Chim. Fr., 23 (1962), there is illustrated the preparation of chlorogallium phthalocyanine by the reaction of o-cyanobenzamide with gallium chloride in the absence of solvent, and hydroxygallium phthalocyanine by dissolution of chlorogallium phthalocyanine in concentrated sulfuric acid, followed by reprecipitation in diluted aqueous ammonia. Further, there are illustrated in JPLO 1-221459 (Toyo Ink Manufacturing) processes for preparing chlorogallium phthalocyanines and hydroxygallium phthalocyanines as well as photoreceptors for use in electrophotography. A number of hydroxygallium phthalocyanine polymorphs and processes for the preparation thereof are described in JPLO 5-263007, the disclosure of which is totally incorporated herein by reference.
More specifically, in Bull. Soc. Chim. Fr., 23 (1962) there is illustrated the preparation of hydroxygallium phthalocyanine via the precursor chlorogallium phthalocyanine. The precursor chlorogallium phthalocyanine is prepared by reaction of o-cyanobenzamide with gallium chloride in the absence of solvent. o-Cyanobenzamide is heated to its melting point (172.degree. C.), and to it is added gallium chloride, at which time the temperature is increased to 210.degree. C. for 15 minutes, and then cooled. The solid is recrystallized out of boiling chloronaphthalene to provide purple crystals having carbon, hydrogen and chlorine analyses matching theoretical values for chlorogallium phthalocyanine. Dissolution in concentrated sulfuric acid, followed by reprecipitation in diluted aqueous ammonia, affords material having carbon and hydrogen analyses matching theoretical values for hydroxygallium phthalocyanine. Further, in JPLO 221459 a photoreceptor for use in electrophotography, comprising a charge generation material and charge transport material on a conductive substrate, and the charge generation material comprising one or a mixture of two or more of gallium phthalocyanine compounds which show the following intense diffraction peaks at Bragg angles (2 theta +/-0.2.degree.) in the X-ray diffraction spectrum,
1--6.7, 15.2, 20.5, 27.0 PA1 2--6.7, 13.7, 16.3, 20.9, 26.3 PA1 3--7.5, 9.5, 11.0, 13.5, 19.1, 20.3, 21.8, 25.8, 27.1, 33.0.
Hydroxygallium phthalocyanine is generally obtained by the hydrolysis of chlorogallium phthalocyanine. Ring chlorination often occurs in the preparation of chlorogallium phthalocyanine as gallium chloride is used at high temperature in the synthesis, which can effect the purity of the final product. These detrimental characteristics can result in detrimental properties when the phthalocyanine is used for high purity applications such as electrophotography. This can be avoided or minimized by using the alkoxy-bridged gallium phthalocyanine dimers of the present invention as the precursor. The alkoxy-bridged gallium phthalocyanine dimer can be hydrolyzed to hydroxygallium phthalocyanine by treatment with sulfuric acid using a procedure similar to that described for the hydrolysis of chlorogallium phthalocyanine in Bull. Soc. Chim. Fr., 23 (1962). The hydroxygallium phthalocyanine can then be converted to the photosensitive Type V hydroxygallium phthalocyanine polymorph as described in copending application U.S. Ser. No. 233,834 the disclosure of which is totally incorporated herein by reference. By selecting an alkoxy-bridged gallium phthalocyanine dimer precursor in the preparation of Type V hydroxygallium phthalocyanine, any negative effects of residual chlorine, or ring chlorination, such as higher dark decay and higher cycledown, are avoided or minimized.
Imaging member applications of alkoxy-bridged metallophthalocyanine dimers, including their use as photogenerator pigments in electrophotographic devices, require commercially viable processes in which the alkoxy-bridged metallophthalocyanine dimers are obtained in high purity, acceptable yields, and with superior electrophotographic properties.
In Konica Japanese 64-17066/89, there is disclosed, for example, the use of a new crystal modification of titanyl phthalocyanine (TiOPc) prepared from alpha-type TiOPc (Type II) by milling it in a sand mill with salt and polyethylene glycol. This publication also discloses that this new polymorph differs from alpha-type pigment in its light absorption and shows a maximum absorbance at 817 nanometers while the alpha-type exhibits a maximum at 830 nanometers. The Konica publication also discloses the use of this new form of TiOPc in a layered electrophotographic device having high photosensitivity at exposure radiation of 780 nanometers. Further, this new polymorph of TiOPc is also described in U.S. Pat. No. 4,898,799 and in a paper presented at the Annual Conference of Japan Hardcopy in July 1989. In this paper, this same new polymorph is referred to as Type Y, and reference is also made to Types I, II, and III as A, B, and C, respectively. Also, in U.S. Ser. No. 169,486, the disclosure of which is totally incorporated herein by reference, there is illustrated a process for the preparation of hydroxygallium phthalocyanine Type V, essentially free of chlorine, whereby a pigment precursor Type I chlorogallium phthalocyanine is prepared by reaction of gallium chloride in a solvent, such as N-methylpyrrolidone, present in an amount of from about 10 parts to about 100 parts, and preferably about 19 parts with 1,3-diiminoisoindoline (DI.sup.3) in an amount of from about 1 part to about 10 parts, and preferably about 4 parts of DI.sup.3 for each part of gallium chloride that is reacted; hydrolyzing said pigment precursor chlorogallium phthalocyanine Type I by standard methods, for example acid pasting, whereby the pigment precursor is dissolved in concentrated sulfuric acid and then reprecipitated in a solvent, such as water, or a dilute ammonia solution, for example from about 10 to about 15 percent; and subsequently treating the resulting hydrolyzed pigment hydroxygallium phthalocyanine Type I with a solvent, such as N,N-dimethylformamide, present in an amount of from about 1 volume part to about 50 volume parts and preferably about 15 volume parts, for each weight part of pigment hydroxygallium phthalocyanine that is used by, for example, ball milling said Type I hydroxygallium phthalocyanine pigment in the presence of spherical glass beads, approximately 1 millimeter to 5 millimeters in diameter at room temperature, about 25.degree. C., for a period of from about 12 hours to about 1 week, and preferably about 24 hours such that there is obtained a hydroxygallium phthalocyanine Type V, which contains very low levels of residual chlorine of from about 0.001 percent to about 0.1 percent, and in an embodiment about 0.03 percent of the weight of the Type V hydroxygallium pigment, as determined by elemental analysis.
Further in U.S. Pat. No. 5,407,766 disclosure of which is totally incorporated herein by reference, there is illustrated a process for the preparation of hydroxygallium phthalocyanine Type V, which comprises formation of a precursor of gallium phthalocyanine, prepared by reaction of 1,3-diiminoisoindoline with gallium acetylacetonate in a suitable solvent solvent; hydrolyzing the precursor by dissolving in a strong acid and then reprecipitating the dissolved pigment in aqueous ammonia, thereby forming Type I hydroxygallium phthalocyanine; and admixing the Type I hydroxygallium phthalocyanine with a polar aprotic organic solvent; and more specifically a process for the preparation of Type V hydroxygermanium phthalocyanine which comprises preparing a precursor gallium phthalocyanine by the reaction of 1,3-diiminoisoindoline with gallium acetylacetonate in a suitable solvent; filtering and, thereafter, washing the pigment precursor gallium phthalocyanine with hot N,N-dimethylformamide, followed by washing with an organic solvent, such as methanol, or acetone; hydrolyzing said precursor by dissolving in a strong acid and then reprecipitating the dissolved pigment in aqueous ammonia, thereby forming Type I hydroxygallium phthalocyanine; and admixing the Type I with the organic solvent N,N-dimethylformamide.
In the following copending patent applications filed concurrently herewith there is illustrated: U.S. Ser. No. 239,432 akoxy-bridged metallophthalocyanine dimers of the formula C.sub.32 H.sub.16 N.sub.8 MOROMN.sub.8 H.sub.16 C.sub.32, or of the formula ##STR4## wherein M is a metal, and R is an alkyl or an alkyl ether; U.S. Ser. No. 233,834 a process for the preparation of Type V hydroxygallium phthalocyanine which comprises the in situ formation of an alkoxy-bridged gallium phthalocyanine dimer, hydrolyzing said alkoxy-bridged gallium phthalocyanine dimer to hydroxygallium phthalocyanine, and subsequently converting the hydroxygallium phthalocyanine product obtained to Type V hydroxygallium phthalocyanine; a process for the preparation of Type V hydroxygallium phthalocyanine which comprises the formation of an alkoxy-bridged gallium phthalocyanine dimer by the reaction of an organic gallium complex with ortho-phthalodinitrile or 1,3-diiminoisoindoline and a diol; hydrolyzing the resulting alkoxy-bridged gallium phthalocyanine dimer to hydroxygallium phthalocyanine, and subsequently converting the hydroxygallium phthalocyanine product obtained to Type V hydroxygallium phthalocyanine; U.S. Ser. No. 233,832 a photoconductive imaging member comprised of an alkoxy-bridged metallophthalocyanine dimer as a charge generator material, wherein the dimer is of the formula C.sub.32 H.sub.16 N.sub.8 MOROMN.sub.8 H.sub.16 C.sub.32 wherein M is a trivalent metal, and R is an alkyl group or an alkyl ether group ##STR5##
The disclosures of all of the aforementioned publications, laid open applications, copending applications and patents are totally incorporated herein by reference.